Don't use premium. You are throwing money away.
The VX is tuned for regular unleaded. I used 85 octane on my roadtrip with no problems whatsoever.
Regular unleaded prices ranged from $2.99 to $3.45 depending on the state and the location...ie, near a highway in California = expensive, but in small towns in Oregon = cheap. Pretty cheap in Utah, too...like around $3.10/gallon. Of course, I mean "cheap" relative to the CA prices. 3000 miles, average 18 MPG, average $3.25 gallon = I probably spent close to $550 on gas for that Moab trip!
Getting out of Seattle for two weeks? PRICELESS.
OEM roof rack, Thule Xpedition 696 rack, Rancho RS9000 shocks, OME 913 coil springs, 3" lift, American Racing Teflon Chambers wheels, Yokohama Geolandar HT/S G051 tires (275/70/16), Energy Suspension greaseable bushings, steel-braided Kevlar-reinforced brake lines, WeatherTech wind deflectors, Malibu 18w driving lights, Plasma SuperWhite 100w headlights, NGK Iridium plugs, K&N drop-in air filter, Optima Red Top, Psychos2 rear-door subwoofer enclosure w/CDT Audio 10" sub, Blaupunkt subwoofer amp, iPod Video 80GB, Kenwood KVT-617 DVD head unit w/7" motorized touch-screen, Kenwood GPS HD navigation module, Kenwood iPod adapter, Kenwood back-up camera, Sirius radio, Flowmaster Extreme Off-Road muffler (black diamond-plate steel) w/ carbon fiber tip, Ford Taurus OEM cup-holder/coin tray (single-DIN/lower bay), personalized license plate "ORBITAL", 3M window tint, debadged, removed rear seat, custom 'radiation symbol' side magnetic signs, VX Concepts front skid plate